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804

Appendix 11.

to any method that substituted a steady pressure for a blow, only
that its rigidity makes water the most suitable medium. It is not,
therefore, introduced on account of its storage, qualities, and in
fact the use of an accumulator or any possibility of a blow is
disallowed at once. In most forging presses, then, the source of
powerósteamólies near the press, and the water is merely a
connection from there to the ram cylinder. The sole advantage
of the system is that time is given for the metal to flow right
through the forging thickness, and that this is no chimera, the
statements of most celebrated engineers admit no doubt of.

Apparently hydraulic forging was suggested by Whitworth's
compression of the fluid steel, and by the objection of his
neighbours to the hammer noise; but it is doubtful whether the
first practical press was due to Haswell, or to Gledhill, Whitworth's
manager. Fig. 768 is a plan of Has well's press, the steam piston

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A being connected directly to the pumps; BB are non-return
" admission valves, and c c delivery valves, worked by powerful
levers from an auxiliary steam cylinder. The piston travels a
whole stroke in either direction alternately, valves cc being opened
or dosed as required, and the water Is exhausted through a fifth
valve, D. A smaller hydraulic ram placed above the main one
serves to lift the latter by means of links. Whitworth's press is
fed directly by steam-driven pumps, though the lifting rams are
worked from an hydraulic accumulator, and his apparatus is easily;